In the related art, there are flat-type lamp units using a GX53-type base. The lamp unit of this type includes a metallic base member, and a light-emitting module having a semiconductor light-emitting element mounted on one surface of the base member, a transmissive cover mounted so as to cover the light-emitting module, the GX53-type base having a pair of lamp pins projected therefrom and mounted on the other surface of the base member, and a lighting circuit accommodated in the base.
However, in the case of such a lamp unit, when increasing a light output using the light-emitting module using large making power, the amount of heat generation of the light-emitting module is increased correspondingly. Therefore, an improvement of radiating performance from the lamp unit is necessary.
In order to improve the radiating performance from the lamp unit, it is conceivable to improve efficiency of heat conduction from the base of the lamp unit toward a lighting fixture with the lamp unit mounted on the lighting fixture. However, with the structure of the lamp unit of the related art, since the base member is interposed between the light-emitting module and the base, efficient conduction of heat from the light-emitting module to the base is not achieved, so that sufficient radiating performance can hardly be obtained.
Also, in order to bring the light-emitting module and the base into contact with each other, part to come into contact with the light-emitting module needs to be projected significantly from the one surface of the base. Consequently, there arises a problem in that the amount of used material of the base is increased, and the mass is increased correspondingly.
It is an object of the invention to provide a lamp unit in which radiating performance is improved while inhibiting an increase in amount of used material and an increase in mass, and a lighting fixture using this lamp unit.